Two Approaches to the Problem of A. Griffith on the Strength of Solids

Abstract

Two approaches to the development of physical models of fracture of solid bodies with cracks are compared, i.e., an energy approach based on the model of A. Griffith and a force approach considering breakage of atomic bonds at the tip of ideally sharp crack. It is shown that it is expedient to amend the contribution of the process of breakage of interatomic bonds into the spent energy by introducing a factor equal to 3 into the classical Griffith formula. An original “force” model of fracture of solid bodies due to ideally sharp cracks of natural origin with allowance for the factor of “rigidity” of interatomic bonds at the tip of the crack is suggested. Results of theoretical computations by both models are compared with experimental data presented in the literature. Explanation of the effect of nanosize cracks on the strength of carbon steels and on the strength of cracked glass tubes and bulbs in Griffith's experiments is suggested as an example.